The present invention relates to a semiconductor substrate and a solid state structure which are used in manufacturing semiconductor integrated circuit devices or the like and which has a similar construction to what is generally called SOI (Silicon On Insulator), and to a method of manufacturing the same. The manufacturing method of the present invention relates, in particular, to the method called recrystallization.
The semiconductor substrate of the present invention can be used in various fields such as highly integrated LSIs, high-voltage-resistant devices, radiation resistant devices and three-dimensional integrated circuits.
Even when the material to be grown into monocrystalline semiconductor film consists of a substance other than silicon, e.g. a compound semiconductor such as GaAs, the structure of the obtained monocrystalline semiconductor film is generally called SOI structure. Likewise, also in the present invention, the material to be grown into the monocrystalline semiconductor film is not restricted to silicon.
Those structures which have been proposed up to now as SOI structures comprise semiconductor films grown on dielectric films or dielectric substrates.
As SOI-structure-forming technology, recrystallization, epitaxial growth, insulating-layer burying method, cladding, etc., are available. As for the SOI-Structure-Forming Technology, a general description thereof is set forth with "SOI-Structure-Forming Technology pp243-247" (published by Sangyo Tosho Kabushiki-Kaisha, 1987).
With respect to recrystallization, there is a method available which is called laser beam recrystallization. According to this method, a polycrystalline or amorphous film formed on a foundation such as an insulating film is melted by the energy of a laser beam, effecting crystal growth while shifting the molten portion.
In order to obtain a monocrystalline film by improving the temperature distribution in the polycrystalline or amorphous film due to the laser beam irradiation, the following attempts have been made:
(a) To improve the temperature distribution within the laser beam spot by using an optical system or a plurality of laser light sources;
(b) To improve the temperature distribution by varying the absorption of the incident laser beam by means of a reflection reducing film or a light absorbing film disposed on the surface of the specimen film; and
(c) To improve the temperature distribution by changing the structure of the specimen to thereby vary local heat dissipation.
While these methods allow some single-crystal film to be obtained, it is still desirable to make it possible to efficiently obtain a single-crystal having a large area.